Various spray devices have been developed by the applicant and others which have been in use for many years. As used herein, the terms “substance” or “medical substance” are intended to broadly cover any vaccine, drug, medicament or other substance which, when applied to a patient, results in the cure, alleviation, suspension, prevention, diagnosis or treatment of a disease or condition of the patient. Such spray devices are commonly limited to a liquid medicament which is stored in a container having a spray head and a pump or the container is formed of a flexible polymer and the liquid is forced through the spray head by squeezing the container. Such spray devices are therefore limited to liquid medicaments having a relatively long shelf life. Syringes with a sprayer have also been developed by the applicant as disclosed in U.S. Pat. No. 5,601,077 assigned to the assignee of the present application.
It is also conventional to store medical substances in a sealed vial or other medical container for later use. Such medicaments may be in a dry, lyophilized (freeze-dried) or powder form to increase shelf life. Such dry, lyophilized or powdered drugs are generally stored in a sealed vial and reconstituted in liquid form for administration to a patient by adding a diluent or solvent. There are also liquid medical substances which are particularly efficacious if mixed prior to use, but the mixture has a relatively short shelf life or liquid medical substances which are not stable after mixing. Conventional medical vials for storing medical substances are generally sealed with an elastomeric stopper and a thin malleable metal cap, such as aluminum, encloses the open end of the vial, which is generally crimped beneath the rim of the vial. A dry, lyophilized or powdered medical substance is normally reconstituted by piercing the elastomeric stopper with the needle cannula of a syringe containing the diluent or solvent. Liquid drugs are also mixed prior to use using a hypodermic syringe containing the second liquid substance as described. This method of reconstituting a dry, lyophilized or powder substance or mixing liquid substances therefore requires the use of several steps and manipulation by the patient or healthcare worker including removal of the aluminum cap and the use of a hypodermic syringe having a sharp needle cannula is subject to potential error, contamination or injury. It would therefore be desirable and convenient for a healthcare worker or patient to have a spray device which mixes the liquid and medical substance, preferably at the time of application and which eliminates the requirement for a syringe having a sharp needle cannula.
It is also conventional to mix a liquid and a medical substance in a syringe prior to injection. Such syringes are generally referred to as “two-component syringe assemblies” and include a syringe barrel typically formed of glass having a needle cannula at one end, a bypass spaced from the needle cannula and the open end and a pair of spaced elastomeric stoppers in the syringe barrel spaced from the bypass as disclosed, for example, in U.S. Pat. Nos. 4,599,082 and 5,899,881 both assigned to the assignee of the present application. The chamber in the syringe barrel defined between the stoppers is generally filled with a liquid and the chamber between the second stopper and the needle cannula may contain a liquid, powder or lyophilized substance, whereby movement of the first stopper drives the second stopper to the bypass area and continued movement of the first stopper drives liquid through the bypass, mixing the liquid with the substance in the second chamber. However, this technology has not been applied or adapted for use in a spray device and prior art spray devices are not adapted for mixing fluid or powder substances at the time of application as set forth above. There is, therefore, a need for a spray device, wherein the medical substance may be mixed in the device, preferably at or near the time of the application of the spray to the patient.